The most prosperous of the five nations of Central America, Guatemala also is the most populous, and the only one in which Indians make up a large portion of the population--by most estimates more than half of the country's 7 million people. Largely disenfranchised by the ruling mestizos, it is only recently that the Indians have become a significant factor in the Guatemalan political equation as guerrillas have sought to persuade them that their situation can be bettered by joining the leftist-led struggle to overthrow the rightist military government.

Following the breakup in 1839 of the United Provinces of Central America, a federation of the five, Guatemala entered a long period of rule by prolonged dictatorships, lasting until Gen. Jorge Ubico was deposed in 1944. A civilian government, backed by liberals and military dissidents, held elected power for the next 10 years. In 1954, President Jacobo Arbenz was ousted by rightist members of the armed forces, assisted by the U.S. Central Intelligence Agency, which feared Arbenz had come under communist influence. Although another civilian government was allowed to take over in 1966, it gradually lost power to the military which, again with U.S. assistance, was waging war against the increasing activity of bands of guerrillas. Amid widespread terrorist activity, Col. Carlos Arana was elected president in 1970. The two elections that followed, in 1974 and 1978, were marked by charges of fraud and brought two additional military regimes to power, including current President Gen. Romeo Lucas Garcia.

During the late 1970s, Guatemala was convulsed by a series of assassinations of centrist and left-center politicians, student, labor and academic leaders. Although the government denied complicity, numerous international human rights organizations have charged official responsibility in what are attributed to military efforts to preserve power by removing possible civilian competition. Meanwhile, the guerrillas, who have grown in strength and numbers, have become increasingly successful in their military challenge to the government and what is seen as a state of incipient civil war now exists.

The Reagan administration, which has charged that the Guatemalan guerrillas are Cuban-inspired and armed, has been blocked by Congressional pressure from reestablishing the strong military relationship suspended by President Carter. The administration hopes that Guatemalan elections scheduled for next Sunday, however, will provide a change in the human rights situation that will allow military assistance to resume.